Organic compounds -- part of the class 532-570 series – Organic compounds – Nitriles
Reexamination Certificate
2002-05-08
2004-06-22
McKane, Joseph K. (Department: 1626)
Organic compounds -- part of the class 532-570 series
Organic compounds
Nitriles
Reexamination Certificate
active
06753440
ABSTRACT:
FIELD OF INVENTION
This invention generally relates to a gas phase process for the hydrocyanation of diolefinic compounds to produce nonconjugated acyclic nitriles. In particular, the invention relates to a gas phase process for the hydrocyanation of diolefinic compounds to produce nonconjugated acyclic nitriles utilizing catalyst compositions comprising copper salts, dispersed on supports, including carbon, silica, alumina and a variety of metal oxides.
BACKGROUND
Catalytic hydrocyanation systems, particularly pertaining to the hydrocyanation of olefins, are known in the art. For example, liquid phase systems useful for the hydrocyanation of butadiene to form pentenenitriles (PNs) are known in the art, e.g., U.S. Pat. No. 3,766,237. As used in that patent and as will be used herein, the term “pentenenitrile” is intended to mean a cyanobutene. Likewise, “butenenitrile” means cyanopropene. The pentenenitriles so formed are further subjected to hydrocyanation and, in some cases isomerization, to form adiponitrile (ADN), a commercially important material in the manufacture of nylon.
The overwhelming majority of prior art processes for the hydrocyanation of butadiene are conducted in the liquid phase, with all attendant waste disposal problems. For example, U.S. Pat. No. 4,240,976 utilized copper halide as a catalyst; U.S. Pat. No. 4,230,634 utilized copper inorganic salts in the presence of organic nitriles; and U.K. Patent No. 2,077,260 used copper bonded to a peroxo group. Previous approaches toward carrying out gas phase hydrocyanation of olefinic compounds have usually started with monoolefinic, not diolefinic, compounds and have given rise primarily to saturated products, which could not be further hydrocyanated. For example, U.S. Pat. No. 3,584,029 teaches that propionitrile is prepared by reaction of HCN with ethylene over catalysts containing Ni salts, H
3
PO
4
and Al
2
O
3
; and U.S. Pat. No. 3,547,972 discloses the reaction of HCN and butadiene in the gas phase over a mixed metal catalyst containing copper chromite and activated copper chromite, which does yield a mixture of pentenenitriles, with 77-82% selectivities to 3-pentenenitrile and 4-pentenenitrile. However, the reaction of U.S. Pat. No. 3,547,972 also requires a co-feed of HCl.
Several patents teach that reaction of HCN with butadiene, ethylene, propylene or butenes, and additionally with air or oxygen in the gas phase, over various supported metal-containing catalysts give rise to cyanated olefinic products. However, in the olefinic products so produced the olefinic double bond is usually conjugated with the triple bond of the cyano group, and, therefore, substantially useless for the production of adiponitrile. For example, see:
U.S. Pat. No. 3,865,863, Asahi, Feb. 11, 1975
U.S. Pat. No. 3,574,701, Asahi K.K.K., Apr. 13, 1971
U.S. Pat. No. 3,578,695, Standard Oil, May 11, 1975
U.S. Pat. No. 3,869,500, Asahi, Mar. 4, 1975
The present invention provides a catalyzed gas phase process for the hydrocyanation of diolefinic compounds which is rapid, selective, and efficient. While certain solvents or diluents can be used in this process, they can be eliminated altogether. Furthermore, the catalyst composition is utilized as a stationary solid phase, which can reduce the cost of catalyst synthesis, recovery, and recycle, as well as the disposal cost of by-product waste. A corollary benefit is the reduction of the cost of capital equipment needed for the process.
SUMMARY OF THE INVENTION
One embodiment of the invention is a process for the gas-phase hydrocyanation of diolefinic compounds comprising reacting an acyclic, aliphatic, conjugated diolefinic compound with HCN in the gas phase within a temperature range of 135° C. to 200° C. in the presence of a catalyst composition that is a supported copper (I) or (II) fluorinated alkylsulfonate complex. Preferably the support used in such a catalyst composition is selected from the group consisting of silica, alumina, and carbon; more preferably the support is silica or carbon. Preferably the fluorinated alkylsulfonate in the copper complex in the catalyst composition is trifluoromethylsulfonate.
Another embodiment of the invention is a process for the gas-phase hydrocyanation of diolefinic compounds comprising reacting an acyclic, aliphatic, conjugated diolefinic compound with HCN in the gas phase within a temperature range of 135° C. to 200° C. in the presence of a catalyst composition that is a copper (I) or (II) complex supported on a fluorosulfonated support. Also preferably the fluorosulfonated support is a composite of a porous silica network within and throughout which is dispersed either a Nafion® perfluorinated polymer or fluorosulfonic acid.
The process in either case is preferably carried out at a temperature of 155-175° C. The starting diolefinic compound is preferably a diolefin represented by the formula R
1
CH═CH—CH═CHR
2
wherein each one of R
1
and R
2
, independently, is H or a C
1
to C
3
alkyl. More preferably the starting diolefinic compound is 1-3-butadiene.
A further embodiment of the invention involves the introduction of HCN and 1,3-butadiene into the reaction without a solvent or diluent. Yet a further embodiment involves dissolving at least one of HCN and 1,3-butadiene in a solvent, inert to the starting materials and to the catalyst composition under the reaction conditions, prior to being introduced into the reaction, with the solution being vaporized prior to its entry into the reaction.
DETAILED DESCRIPTION OF THE INVENTION
A catalyst composition useful in the practice of the present invention includes a copper (I) or (II) fluorinated alkylsulfonate complex supported on a carrier that is neutral and has a low surface area. A complex is one or more metal cations together with its associated anions. A preferred support is silica, alumina, carbon and the like. Commonly used techniques for treatment of supports with metal catalysts can be found in B. C. Gates,
Heterogeneous Catalysis,
Vol. 2, pp. 1-29, Ed. B. L. Shapiro, Texas A & M University Press, College Station, Tex., 1984. Typically, in accordance with this invention, the copper (I) or (II) fluorinated alkylsulfonate complex is dispersed on a silica, alumina or carbon support at a concentration sufficient to produce a catalyst composition, including the support, containing 0.3% wt. to 1.0% wt. copper by weight of the total of the composition.
Fluorinated alkylsulfonates useful in forming a complex with copper include anions or dianions of the structure R—SO
3
−
or R—(SO
3
−
)
2
, where R is a linear or branched polyfluoroalkyl or a perfluoroalkyl group of up to 12 carbon atoms. Preferably R is trifluoromethyl. Anions of the type (R—SO
3
)
2
N
−
or F—SO
3
−
may also be used in place of alkylsulfonates. Nitrile ligands may also be complexed to copper.
Catalyst compositions useful in the practice of the present invention also include copper (I) or (II) complexes supported on a fluorosulfonated support. A fluorosulfonated support contains R—SO
3
−
groups, where R is as defined above or is —C
n
F
2n
—. Preferably the fluorosulfonated support is a composite of a porous silica network within and throughout which is dispersed either a Nafion® perfluorinated polymer or fluorosulfonic acid. Such a composite is more particularly described in U.S. Pat. Nos. 5,824,622, 5,916,837 and 5,948,946.
In the process of the invention, the catalyst composition is loaded into a tubular reactor, and a gaseous diolefinic compound, e.g., butadiene, and HCN are passed continuously over the solid catalyst composition at a temperature sufficiently high to maintain the starting materials as well as the reaction products in the gas phase. The preferred temperature range is from about 135° C. to about 200° C., most preferably from about 155° C. to about 175° C. The temperature must be high enough to maintain all of the reactants and products in the gas phase but low enough to prevent deterioration of the catalyst composition. The particular preferred temperature depends t
Druliner Joe Douglas
Harmer Mark Andrew
Herron Norman
LeCloux Daniel
E.I. du Pont de Nemours and Company
McKane Joseph K.
Sackey Ebenezer
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